A hydraulic auxiliary system for the cooling bed of a heavy plate rolling mill and its control method

Abstract

This invention discloses an auxiliary hydraulic system for the cooling bed of a heavy plate rolling mill and its control method, relating to the technical field of heavy plate rolling mill equipment. The system includes: a cooling bed auxiliary feeding and lifting actuator, a control circuit for the lifting cylinder of the cooling bed feeding device, an oil tank, and multiple sets of pump units, each with an identical structure. The auxiliary feeding and lifting actuator, the oil tank, and the multiple sets of pump units are respectively connected to the control circuit for the lifting cylinder of the cooling bed feeding device. In the pump units, a gear pump is connected to a synchronous AC servo motor via a coupling and a bell-shaped cover; a servo driver is connected to the synchronous AC servo motor; pressure sensors are installed on the parallel pipelines at the outlet of each pump unit, and the feedback signals from the pressure sensors can be input to the servo driver for pressure control. This invention overcomes the problems of overheating and high energy loss in existing auxiliary hydraulic systems for the cooling bed of heavy plate rolling mills.

Description

Technical Field

[0001] This invention relates to the field of heavy plate rolling mill equipment, and in particular to an auxiliary hydraulic system for the cooling bed of a heavy plate rolling mill line and its control method. Background Technology

[0002] A heavy plate rolling mill is a large-scale mechanical equipment mainly used for rolling medium-thickness steel plates. It consists of upper and lower work rolls, a transmission system, a control system, and auxiliary systems. The main operations of the heavy plate rolling mill line are all controlled by an advanced hydraulic system, which offers advantages such as automated operation, high efficiency, and stable reliability. The cooling bed auxiliary hydraulic system is a crucial core component of the entire heavy plate rolling mill line's hydraulic system, primarily controlling the lifting and lowering of the hydraulic cylinders of the cooling bed loading devices at various nodes.

[0003] Currently, the most widely used and prevalent auxiliary hydraulic systems for cooling beds in the domestic rolling mill market employ a three-phase asynchronous motor combined with a piston pump. In this type of hydraulic system, the motor continues to run at high speed during waiting or pressure-holding processes, resulting in significant energy waste and widespread overheating. Furthermore, the control principle of the lifting cylinder in the cooling bed loading device of many current rolling mill models consists of a proportional valve plus two externally controlled, externally leaking check valves connected to the A and B ports of the proportional valve, and a solenoid directional valve controlling these two externally controlled, externally leaking check valves. Proportional control is complex and has high requirements for the contamination level of the hydraulic system medium. Summary of the Invention

[0004] In view of this, the present invention provides an auxiliary hydraulic system for the cooling bed of a heavy plate rolling mill and its control method, aiming to overcome the problems of heat generation and large power loss in the existing auxiliary hydraulic system for the cooling bed of a heavy plate rolling mill; since a proportional directional valve is not used, the level of hydraulic medium contamination can be reduced, and the hydraulic control principle of the lifting cylinder of the cooling bed feeding device is improved, so that the lifting cylinder of the cooling bed feeding device can operate efficiently, stably, and in a green and energy-saving manner.

[0005] Therefore, the present invention provides the following technical solution:

[0006] On the one hand, the present invention also provides an auxiliary hydraulic system for the cooling bed of a heavy plate rolling mill. The system includes: a cooling bed auxiliary loading and lifting actuator, a cooling bed loading device lifting cylinder control circuit, an oil tank device, and multiple sets of pump sets, each set of pump sets having the same structure.

[0007] The cooling bed auxiliary loading and lifting actuator, the oil tank device, and the multiple pump sets are respectively connected to the lifting cylinder control circuit of the cooling bed loading device;

[0008] In the pump set, the gear pump is connected to the synchronous AC servo motor via a coupling and a bell-shaped cover. The servo driver is connected to the synchronous AC servo motor. Pressure sensors are installed on the parallel pipelines at the outlet of each pump set. The feedback signal from the pressure sensors can be input to the servo driver for pressure control.

[0009] Furthermore, in the control circuit of the lifting cylinder of the cooling bed loading device, the A port and B port of the electro-hydraulic directional valve are respectively connected to the A port of the hydraulic control check valve, the oil port B of the hydraulic control check valve is respectively connected to the rodless chamber and the rod chamber of the lifting cylinder of the cooling bed loading device, the oil port T of the check valve is connected to the rod chamber of the lifting cylinder of the cooling bed loading device, and the electromagnetic relief valve is a high-pressure relief control valve from the rodless chamber of the lifting cylinder of the cooling bed loading device to the oil port T.

[0010] Furthermore, after inputting command signals through the host PLC, the servo drive controls and adjusts the pressure and speed of the gear pump based on the pressure from the hydraulic system pump outlet pressure sensor and the feedback signal from the resolver encoder built into the synchronous AC servo motor, outputting the pressure and flow rate actually required by the system.

[0011] Furthermore, during the synchronous AC servo motor control process, based on PID regulation, the servo driver executes a speed closed-loop control mode before the set pressure is reached, and the synchronous AC servo motor rotates at the set maximum speed; when the set pressure is reached, the servo driver executes a pressure closed-loop control mode, and the servo system is only responsible for maintaining constant pressure and adaptive speed.

[0012] In another aspect, the present invention also provides a control method for an auxiliary hydraulic system of a cooling bed in a heavy plate rolling mill, the method comprising:

[0013] S1. The host computer PLC inputs pressure P1 and flow Q1 commands to the servo driver, and the synchronous AC servo motor rotates in the forward direction. Electromagnets YH01~YH06 and YH1b are energized, and YH2a is energized to open the hydraulic control check valve. The pressure oil enters the rodless chamber of the lifting cylinder of the cooling bed loading device through the oil port P→A of the electro-hydraulic reversing valve, which lifts the actuator.

[0014] S2. According to PID adjustment, before the set pressure is reached, the servo driver executes the speed closed-loop control mode, and the synchronous AC servo motor rotates at the set high speed.

[0015] S3. When the lifting cylinder of the cooling bed feeding device extends to the equipment accessory position, the displacement sensor of the lifting cylinder of the cooling bed feeding device sends a signal to synchronously rotate the AC servo motor at a set low speed and low pressure to prevent the equipment from being damaged by excessive pressure or speed.

[0016] S4. When the lifting cylinder of the cooling bed feeding device continues to extend to the final set position, the displacement sensor of the lifting cylinder of the cooling bed feeding device sends a signal, the electromagnet YH1b is de-energized, YH2a is de-energized and closes the hydraulic control check valve, and the lifting cylinder of the cooling bed feeding device stops moving.

[0017] S5. When electromagnets YH01~YH06 and YH1b are energized and YH2a is energized to open the hydraulic check valve, the lifting cylinder of the cooling bed loading device retracts by the weight of the actuator, the AC servo motor rotates in the reverse direction, and the hydraulic oil enters the oil tank through the rodless chamber of the lifting cylinder of the cooling bed loading device via the oil port A→P of the electro-hydraulic reversing valve and the gear pump rotates in the reverse direction.

[0018] S6. Under the pressure of the actuator's own weight, the gear pump preferentially rotates in the reverse direction at high speed. However, the AC servo motor relies on a lower reverse speed set by instructions. Through the reverse force between the motor shaft and the gear pump shaft, back pressure is formed in the hydraulic oil P line, lifting the actuator to decrease its speed according to the set speed of the AC servo motor. The retraction speed of the lifting cylinder of the cooling bed loading device is achieved by the reverse speed of the AC servo motor according to process requirements.

[0019] S7. When the lifting cylinder of the cooling bed feeding device retracts to the set position, the displacement sensor of the lifting cylinder of the cooling bed feeding device sends a signal, the electromagnet YH1b is de-energized, YH2a is de-energized and closes the hydraulic control check valve, and the lifting cylinder of the cooling bed feeding device stops operating.

[0020] Advantages and positive effects of the present invention:

[0021] This invention employs novel energy-saving control technology, employing a synchronous AC servo motor paired with a gear pump control principle. The AC servo driver automatically adjusts the motor speed, enabling the hydraulic station to perform closed-loop pressure and speed control based on pressure and speed feedback signals during operation. The feedback pressure is compared with the required pressure, and the servo controller adjusts the output speed and torque of the synchronous motor according to the feedback signal, ensuring the system pressure follows the set value. When the required flow rate changes, the servo motor speed changes accordingly, altering the pump's displacement. During standby or pressure holding, sensors detect the current pressure in the main oil pipeline. If the pressure exceeds the target set value, the servo driver controls the motor to operate at low speed or stop, resulting in a small or zero displacement pump output. The main oil pipeline pressure is maintained by the system's accumulator. This reduces energy loss from continuous high-speed motor rotation, lowers system heat generation, avoids hydraulic system leaks caused by high temperatures, reduces environmental pollution, extends the service life of seals in the hydraulic system, and saves significant amounts of electricity, achieving a comprehensive energy-saving and emission-reduction effect. When the load changes and the pressure is lower than the set value, the servo controller receives the pressure feedback signal and controls the motor to start quickly to a certain speed. At this time, the oil pump output flow and the accumulator work at the same time to ensure that the pressure in the main oil pipe is always kept at the target value. This cycle continues to work to ensure stable operation of the equipment.

[0022] Furthermore, in this invention, an electro-hydraulic directional valve is used instead of a proportional directional valve in the lifting control principle of the cooling bed loading device, which reduces proportional control, lowers the complexity of electrical control, greatly improves the reliability of the cooling bed auxiliary hydraulic system, simplifies the hydraulic system structure, and reduces the system oil contamination level from NAS1638-7 to NAS1638-9. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the hydraulic system of the cooling bed auxiliary pump station in an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of the hydraulic system of the cooling bed auxiliary valve station in an embodiment of the present invention;

[0026] Figure 3 This is a simplified diagram of the cooling bed auxiliary feeding and lifting actuator in an embodiment of the present invention;

[0027] In the diagram, 1. Oil tank; 2. Pressure test connector; 3. Return oil filter; 4. Heater; 5. Sampling ball valve; 6. Air filter; 7. Drain ball valve; 8. Check valve; 9. Temperature sensor; 10. Ball valve; 11. Level relay; 12. Drain ball valve; 13. Check valve; 14. Rubber hose; 15. Signal butterfly valve; 16. Rubber expansion joint; 17. Ball valve; 18. Rubber hose; 19. Gear pump; 20. Coupling; 21. Bell housing; 22. Synchronous AC servo motor; 23. Servo driver; 24. High 25. Pressing hose; 26. High-pressure filter; 27. Check valve; 28. Solenoid relief valve; 29. ​​Check valve; 30. High-pressure ball valve; 31. Pressure testing hose; 32. Pressure gauge; 33. Pressure sensor; 34. High-pressure ball valve; 35. Check valve; 36. Electro-hydraulic directional valve; 37. Solenoid directional valve; 38. Hydraulic check valve; 39. Check valve; 40. Relief valve; 41. Lifting cylinder with displacement sensor; 42. Lifting cylinder for cooling bed loading device; 43. Crankshaft mechanism; 44. Lifting actuator. Detailed Implementation

[0028] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0029] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0030] This invention solves the problems of overheating and high energy loss in the existing auxiliary hydraulic system of the cooling bed by improving the existing hydraulic system and its control method. It also reduces the level of hydraulic medium contamination and simplifies the hydraulic control principle of the lifting cylinder of the cooling bed loading device, enabling the lifting cylinder of the cooling bed loading device to operate efficiently, stably, and in an energy-saving manner.

[0031] This invention employs a novel energy-saving control technology, utilizing an AC servo motor paired with a gear pump control principle, falling under the category of electro-hydraulic servo systems. The AC servo driver automatically adjusts the motor speed, enabling the hydraulic station to perform closed-loop pressure and speed control based on pressure and speed feedback signals during operation. The feedback pressure is compared with the required pressure, and the servo controller adjusts the output speed and torque of the synchronous motor according to the feedback signal, ensuring the system pressure follows the set value. When the required flow rate changes, the servo motor speed changes accordingly, altering the pump's displacement. During standby or pressure holding, the sensor detects the current pressure in the main oil pipeline. If the pressure exceeds the target set value, the servo driver controls the motor to operate at low speed or stop, resulting in a small or zero displacement pump output. The main oil pipeline pressure is maintained by the system's accumulator. This reduces energy loss from continuous high-speed motor rotation, lowering system heat generation and achieving energy savings. When the load changes and the pressure drops below the set value, the servo controller receives a pressure feedback signal and controls the motor to quickly start up to a certain speed. At this time, the oil pump output flow and the accumulator work simultaneously to ensure that the pressure in the main oil pipe remains at the target value. This cycle continues to ensure stable equipment operation. Furthermore, in the control principle of the lifting cylinder of the cooling bed loading device, a conventional electro-hydraulic directional valve replaces the proportional directional valve. This allows the servo motor to replace proportional control in controlling the cylinder's lifting speed, reducing product costs and making the control of the lifting cylinder of the cooling bed loading device simpler and more efficient.

[0032] like Figures 1-3As shown, the cooling bed auxiliary hydraulic system in this embodiment of the invention mainly includes: a cooling bed auxiliary loading and lifting actuator, a cooling bed loading device lifting cylinder control circuit, an oil tank device, and multiple pump sets, each with the same structure. The main components include: oil tank 1, pressure test connector 2 (2.1), return oil filter 3, heater 4 (4.1, 4.8), sampling ball valve 5 (5.1, 5.2), air filter 6 (6.1, 6.2), drain ball valve 7 (7.1, 7.2), check valve 8, temperature sensor 9, ball valve 10 (10.1), level relay 11, drain ball valve 12 (12.1), check valve 13 (13.1), hose 14 (14.1), signal butterfly valve 15 (15.1), rubber expansion joint 16 (16.1), ball valve 17 (17.1), hose 18 (18.1), gear pump 19, and coupling 20 (20.1). Bell-shaped jar 21 (21.1), synchronous AC servo motor 22 (22.1), servo driver 23 (23.1), high-pressure hose 24 (24.1), high-pressure filter 25 (25.1), one-way valve 26 (26.1), electromagnetic relief valve 27 (27.1), one-way valve 28 (28.1), high-pressure ball valve 29 (29.1), pressure measuring hose 30 (30.1), pressure gauge 31 (31.1), pressure sensor 32, high-pressure ball valve 33, check valve 34, one-way valve 35, electro-hydraulic directional valve 36, electromagnetic directional valve 37, hydraulic control one-way valve 38, one-way valve 39, relief valve 40, and cooling bed lifting cylinder with displacement sensor 41.

[0033] Specifically, such as Figure 1 As shown, in the pump unit, the gear pump 19 is connected to the synchronous AC servo motor 22 through the coupling 20 and the bell-shaped cover 21. The servo driver 23 is connected to the synchronous AC servo motor 22. The pressure sensor 32 is installed on the parallel pipeline of the outlet of the seven pump units. The feedback signal of the pressure sensor 32 can be input to the servo driver 23 for pressure control.

[0034] High-pressure filter 25 is connected to gear pump 19 via high-pressure hose 24 (24.1). High-pressure filter 25, check valve 26 (26.1), and high-pressure ball valve 29 (29.1) are connected in sequence. The other end of high-pressure ball valve 29 (29.1) is connected to the control circuit of lifting cylinder of cooling bed loading device. Pressure gauge 31 (31.1) is installed between high-pressure ball valve 29 and check valve 26 via pressure measuring hose 30 (30.1). Electromagnetic relief valve 27 (27.1) is also connected to gear pump 19 via high-pressure hose 24 (24.1). Electromagnetic relief valve 27 is connected to check valve 28 (28.1). The other end of check valve 28 is connected to the control circuit of lifting cylinder of cooling bed loading device.

[0035] The main components of the oil tank device are oil tank 1 (1.0), and the oil tank 1 is surrounded by oil return filter 3, heater 4 (4.1, 4.8), sampling ball valve 5 (5.1, 5.2), air filter 6 (6.1, 6.2), drain ball valve 7 (7.1, 7.2), check valve 8, temperature sensor 9, ball valve 10 (10.1, 10.2), and liquid level relay 11.

[0036] like Figure 2 As shown, in the control circuit of the lifting cylinder of the cooling bed loading device, the A port and B port of the electro-hydraulic directional valve 36 are connected to the A port of the hydraulic control check valve 38 (38.1 and 38.2) respectively. The oil port B of the hydraulic control check valve 38 (38.1 and 38.2) is connected to the rodless chamber and the rod chamber of the lifting cylinder 41 of the cooling bed loading device respectively. The check valve 39 is connected to the oil port T and the rod chamber of the lifting cylinder 41 of the cooling bed loading device. The electromagnetic relief valve 37 is a high-pressure relief control valve from the rodless chamber of the lifting cylinder 41 of the cooling bed loading device to the oil port T.

[0037] like Figure 3 As shown, the cooling bed auxiliary loading and lifting actuator mainly includes: a lifting cylinder 42 for the cooling bed loading device, a crankshaft mechanism 43, and a lifting actuator 44.

[0038] In the above structure, the power source design of the pump station uses a synchronous AC servo motor 22 paired with a gear pump 19 and a pressure sensor 32 to form a small closed-loop branch. Since the synchronous AC servo motor 22 itself has a rotary encoder, after inputting command signals through the host PLC, the servo driver 23 controls and adjusts the pressure and speed of the gear pump 19 based on the pressure from the hydraulic system pump outlet pressure sensor 32 and the feedback signal from the rotary encoder built into the synchronous AC servo motor 22, outputting the actual pressure and flow rate required by the system. During the control process of the synchronous AC servo motor 22, according to PID regulation, before the set pressure is reached, the servo driver 23 executes a speed closed-loop control mode, and the synchronous AC servo motor 22 rotates at the set maximum speed. When the set pressure is reached, the servo driver 23 executes a pressure closed-loop control mode, where the servo system is only responsible for maintaining constant pressure, and the speed is adaptive. Furthermore, the synchronous AC servo motor 22 possesses characteristics such as low speed, standby, field weakening speed amplification, multi-stage speed, high overload capacity, and fast response. Therefore, in the standby or pressure-holding state of the cooling bed auxiliary hydraulic system, the synchronous AC servo motor 22 rotates at low speed or stops, allowing the pump to output at a small or zero displacement, while the main oil pipe pressure is maintained by the system's accumulator. Since the flow rate required by the hydraulic system actuator varies during operation, when the required flow rate changes, the speed of the synchronous AC servo motor 22 changes accordingly with the magnitude of the flow command, achieving flow self-adaptation. This avoids continuous high-speed rotation of the motor under different operating flow rates, reduces system heat generation, and eliminates the disadvantages of the cooling bed auxiliary hydraulic system, such as large size, high heat generation, and high energy consumption.

[0039] Under the above structure, the proportional directional valve controlling the lifting speed of the cooling bed loading device is eliminated in the control circuit of the lifting cylinder. Since a servo motor closed-loop system is adopted, after the upper computer PLC inputs the instruction signal, it provides the appropriate flow and pressure according to the actual needs of the lifting cylinder of the cooling bed loading device. Therefore, the system heat generation is reduced, and the complex control of the proportional valve is also reduced.

[0040] Because proportional control has been eliminated in the entire cooling bed auxiliary control system, the contamination level of the hydraulic medium in the cooling bed auxiliary hydraulic system has been directly reduced from NAS1638-7 to NAS1638-9, which greatly improves the performance of the entire cooling bed auxiliary hydraulic system and reduces maintenance costs.

[0041] Combination Figure 1 and Figure 2 The detailed control method and process of the lifting cylinder of the feeding device in the auxiliary hydraulic system of the cooling bed are as follows:

[0042] S1. The host PLC inputs pressure P1 and flow Q1 commands to the servo driver 23, causing the synchronous AC servo motor 22 to rotate in the forward direction. Electromagnets (YH01~YH06) and YH1b are energized, and YH2a is energized to open the hydraulic control check valves 38.1 and 38.2. The pressure oil enters the rodless chamber of the lifting cylinder 41 of the cooling bed loading device through the oil port P→A of the electro-hydraulic directional valve 36, lifting the actuator.

[0043] S2. According to PID adjustment, before the set pressure is reached, the servo drive 23 executes the speed closed-loop control mode, and the synchronous AC servo motor 22 rotates at the set high speed.

[0044] S3. When the lifting cylinder 41 of the cooling bed loading device extends to the equipment accessory position, the displacement sensor of the lifting cylinder 41 of the cooling bed loading device sends a signal, and the AC servo motor 22 rotates at a set low speed and low pressure to prevent the equipment from being damaged by excessive pressure or speed.

[0045] S4. When the lifting cylinder 41 of the cooling bed feeding device continues to extend to the final set position, the displacement sensor of the lifting cylinder 41 of the cooling bed feeding device sends a signal, the electromagnet YH1b is de-energized, the YH2a is de-energized and closes the hydraulic control check valves 38.1 and 38.2, and the lifting cylinder 41 of the cooling bed feeding device stops operating.

[0046] S5. When electromagnets (YH01~YH06) and YH1b are energized and YH2a is energized to open hydraulic control check valves 38.1 and 38.2, the lifting cylinder 41 of the cooling bed loading device retracts by its own weight, the AC servo motor 22 rotates in the reverse direction, and the hydraulic oil flows from the rodless chamber of the lifting cylinder 41 of the cooling bed loading device through the oil port A→P of the electro-hydraulic directional valve 36, and enters the oil tank through the gear pump 19 rotating in the reverse direction.

[0047] S6. Under the pressure of the actuator's own weight, gear pump 19 preferentially rotates in the reverse direction at high speed. However, AC servo motor 22, relying on a command-set lower reverse speed, creates back pressure in the hydraulic oil P line through the reverse force between the motor shaft and the gear pump 19 shaft, lifting the actuator to decrease its speed according to the set speed of AC servo motor 22. The retraction speed of the lifting cylinder 41 of the cooling bed loading device is achieved by the reverse speed of AC servo motor 22 according to process requirements.

[0048] S7. When the lifting cylinder 41 of the cooling bed feeding device retracts to the set position, the displacement sensor of the lifting cylinder 41 of the cooling bed feeding device sends a signal, the electromagnet YH1b is de-energized, the YH2a is de-energized and closes the hydraulic control check valves 38.1 and 38.2, and the lifting cylinder 41 of the cooling bed feeding device stops operating.

[0049] The solutions described in the above embodiments are applicable to the auxiliary hydraulic systems of cooling beds in various types of wide and thick plate rolling mills.

[0050] The above embodiments have the following beneficial effects:

[0051] (1) A novel energy-saving control technology is adopted, which constitutes a synchronous AC servo motor with gear pump control principle. The AC servo driver automatically adjusts the motor speed, so that the hydraulic station can perform closed-loop control of pressure and speed according to the pressure feedback signal and speed feedback signal during operation. The feedback pressure is compared with the demand pressure, and the servo controller will adjust the output speed and torque of the synchronous motor according to the feedback signal, so that the system pressure follows the set value. When the required flow rate of the system changes, the speed of the servo motor changes with the size of the flow command, so that the pump displacement changes. When the hydraulic station is in standby or holding pressure, the sensor will detect the current pressure in the main oil pipeline. If the pressure exceeds the target set value, the servo driver will control the motor to be in a low speed or stop state, so that the pump outputs small displacement or zero displacement, and the main oil pipeline pressure is maintained by the system accumulator. This reduces the energy loss caused by the continuous high speed rotation of the motor, reduces the system heat generation, avoids the leakage problem of the hydraulic system caused by high temperature, reduces the pollution of the working environment, extends the service life of the seals in the hydraulic system, and saves a lot of electricity, achieving a comprehensive effect of energy saving and emission reduction, and in line with the national green environmental protection policy. When the load changes and the pressure is lower than the set value, the servo controller receives the pressure feedback signal and controls the motor to start quickly to a certain speed. At this time, the oil pump output flow and the accumulator work at the same time to ensure that the pressure in the main oil pipe is always kept at the target value. This cycle continues to work to ensure stable operation of the equipment.

[0052] (2) In terms of the lifting control principle of the cooling bed feeding device, the electro-hydraulic directional valve is used instead of the proportional directional valve, which reduces the proportional control and the complexity of electrical control, greatly improves the reliability of the cooling bed auxiliary hydraulic system, simplifies the hydraulic system structure, and reduces the system oil contamination level from NAS1638-7 to NAS1638-9.

[0053] This invention can be widely applied to the renovation of existing heavy plate rolling mill lines and the installation of new equipment. It ensures system reliability and can effectively reduce related maintenance and replacement costs caused by system overheating, including labor costs, hoisting costs, and spare parts procurement costs. At the same time, due to the reduced failure rate of this type of product, it is highly energy-efficient and environmentally friendly.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A wide and heavy plate mill cooling bed auxiliary hydraulic system, characterized by, The system comprises a cold bed auxiliary loading lifting actuator, a cold bed loading device lifting cylinder control circuit, an oil tank device and a plurality of pump group devices, each of which has the same structure; The cold bed auxiliary loading lifting actuator, the oil tank device and the plurality of pump group devices are connected with the cold bed loading device lifting cylinder control circuit respectively; In the pump group device, the gear pump (19) is connected with the synchronous alternating current servo motor (22) through the shaft coupling (20) and the bell cover (21), the servo driver (23) is connected with the synchronous alternating current servo motor (22), the pressure sensor (32) is installed on the outlet of each pump group device and the parallel pipeline, and the feedback signal of the pressure sensor (32) can be input into the servo driver (23) for pressure control; in the cold bed loading device lifting cylinder control circuit, the A port and the B port of the electro-hydraulic reversing valve (36) are connected with the A ports of the hydraulic control check valve one (38.1) and the hydraulic control check valve two (38.2) respectively, the oil ports B of the hydraulic control check valve one (38.1) and the hydraulic control check valve two (38.2) are connected with the rodless cavity and the rod cavity of the cold bed loading device lifting cylinder (41) respectively, the check valve (39) is connected with the oil port T and the rod cavity of the cold bed loading device lifting cylinder (41), and the electromagnetic overflow valve (37) is the high-pressure overflow control valve of the rodless cavity of the cold bed loading device lifting cylinder (41) to the oil port T; after the upper computer PLC inputs the instruction signal, the servo driver (23) controls and adjusts the pressure and the rotating speed of the gear pump (19) according to the pressure of the hydraulic system pump outlet pressure sensor (32) and the feedback signal of the rotary encoder of the synchronous alternating current servo motor (22), and outputs the actual required pressure and flow of the system; in the synchronous alternating current servo motor (22) control process, according to the PID regulation, before the set pressure is reached, the servo driver (23) executes the speed closed loop control mode, and the synchronous alternating current servo motor (22) rotates at the set maximum rotating speed; when the set pressure is reached, the servo driver (23) executes the pressure closed loop control mode, and the servo system only maintains the constant pressure and the adaptive speed.

2. A control method for a wide and heavy plate mill cooling bed auxiliary hydraulic system based on claim 1, characterized by, The method comprises: S1, the upper computer PLC inputs the pressure P1 and the flow Q1 instructions to the servo driver (23), the synchronous alternating current servo motor (22) rotates forward, the electromagnets YH01-YH06 and YH1b are electrified, the YH2a is electrified to open the hydraulic control check valve one (38.1) and the hydraulic control check valve two (38.2), the pressure oil enters the rodless cavity of the cold bed loading device lifting cylinder (41) through the oil port P-A of the electro-hydraulic reversing valve (36), and the actuator is lifted; S2, according to the PID regulation, before the set pressure is reached, the servo driver (23) executes the speed closed loop control mode, and the synchronous alternating current servo motor (22) rotates at the set high rotating speed; S3、When the cold bed loading device lifting oil cylinder (41) extends to the equipment accessory position, the displacement sensor of the cold bed loading device lifting oil cylinder (41) sends a signal, and the synchronous alternating current servo motor (22) rotates at a set low speed and low pressure to prevent the equipment from being damaged by excessive pressure or speed; S4、When the cold bed loading device lifting oil cylinder (41) continues to extend to the final set position, the displacement sensor of the cold bed loading device lifting oil cylinder (41) sends a signal, the electromagnet YH1b loses power, YH2a loses power to close the hydraulic control check valve one (38.1) and the hydraulic control check valve two (38.2), and the cold bed loading device lifting oil cylinder (41) stops working; S5、When electromagnets YH01-YH06 and YH1b are powered on, YH2a is powered on to open hydraulic control check valve one (38.1) and hydraulic control check valve two (38.2), the cold bed loading device lifting oil cylinder (41) is retracted by the weight of the actuator, the alternating current servo motor (22) is reversed, and the hydraulic oil enters the tank through the oil port A→P of the electro-hydraulic reversing valve (36) from the rodless cavity of the cold bed loading device lifting oil cylinder (41) through the reverse rotation of the gear pump (19); S6、The gear pump (19) is first high-speed reverse rotation under the pressure of the weight of the actuator, but the alternating current servo motor (22) relies on the lower reverse speed set by the command to form back pressure in the hydraulic oil P pipeline through the reverse force of the motor shaft and the gear pump (19) shaft, and the actuator is lifted according to the set speed of the alternating current servo motor (22); The cold bed loading device lifting oil cylinder (41) retraction speed is realized according to the reverse speed of the alternating current servo motor (22) according to the process requirement; S7、When the cold bed loading device lifting oil cylinder (41) is retracted to the set position, the displacement sensor of the cold bed loading device lifting oil cylinder (41) sends a signal, the electromagnet YH1b loses power, YH2a loses power to close the hydraulic control check valve one (38.1) and the hydraulic control check valve two (38.2), and the cold bed loading device lifting oil cylinder (41) stops working.

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